Variable pitch propeller



Jam 20, 1933. M. M. MUNK 1,914,754

VARIABLE PITCH P-ROPELLER Filed July 10, 1931 Patented June 20, 1933M'AX M. MUNK, OF WASHINGTON, DISTRICT OF COLUMBIA VARIABLE PITCHPROPELLER I Application filed July 10,

very large centrifugal forces and the constructions so far proposed havetheir bearing surfaces loaded by the centrifugal forces. As a result,excessive friction is developed between the moving parts and it isnecessary to use a large force in order to adjust the propellers.

Itis an object of the present invention to provide a propeller which isadjustable during operation, all bearing surfaces of which are free fromcentrifugal forces.

Another objectof this invention is to provide a propeller havinglongitudinally split blades, corresponding pairs of blade portionsforming individual units balanced by themselves.

Still another object of this invention is to provide a propellerconsisting of portions 7 adjustable relative to each other by rotation35 about the main propeller axis.

With these and other objects in view. which may be incident to myimprovements, the invention consists in the parts andcombinations to behereinafter set forth and claimed.

g with the understanding that the several necessary elements, comprisingmy invention, may be varied in construction, proportions andarrangement, without departing from the spirit and scope of the appendedclaims.

,6 In order to make my invention more clearly understood, I have shownin the accompanying drawing means for carrying the same into practicaleffect, without limiting the improvements in their useful applica- 50tions to the particular constructions, which 1931. Serial No. 550,011.

for the purpose of explanation, have been made the subject ofillustration.

In the drawing like numerals refer to similar parts throughout theseveral views, of which 55 Fig. 1 represents a cross section through thecenter of a propeller along the main propeller axis and a pair ofblades;

Fig. 2 shows a cross section through line 2-2 of Fig. 1, and F 1g. 3 isa cross sectional view through the propeller along the line 33 of Fig.1.

Referring to the drawing, and more particularly to Fig. 1 thereof, themain body of the propeller is shown as being split or di- 6 vided intotwo portions, 1 and 2. The front portion 1 is keyed to the driving shaft3 and secured thereto by means of a washer 4. and lock nut 5 whichpresses the front portion of the propeller against the collar 6 of theshaft 3. The propeller portion, 1, consists of the hub 1a, the bladeportions 15 and 10, all three parts being formed integrally of lightmetal.

On the rear extension of the hub 1a is rotatably mounted the hub 2a ofthe propeller portion 2, which hub is formed integrally with the twoblades portions 2?) and 20. A ring 7, fastened to the hub 1w by means ofpins 8, prevents any axial motion between the propeller portions 1 and2. Between the two rear extensions of the hubs 1a and 2a is inserted abearing or flanged sleeve 9 interlocking with the extensions 1a and 2aby means of spiral keys 9a and 9b fitting into corresponding spiralgrooves of the hub extensions. The spirals 9a are right handed and thespiral keys 9b are left handed. All parts so far mentioned rotate withthe propeller and its shaft.

The flange of the sleeve 9 is held in axial position by a nut 10 whichmay be screwed along the outside thread of the bearing 11 by means of ahand crank 12, the shaft 13 and the cog wheel 14 in mesh with the nut10. The ring 15 attached to the nut 10 by means of bolts, 16, eliminatesany axial motion between the nut 10 and the sleeve 9,

without interfering with the rotation of the 109 sleeve relative to thestationary nut when the hand crank 12 is turned.

In order to increase the rigidity of the propeller, the two adjacentparts of the blade may be dovetailed as shown at 16. I

When the hand crank is turned the nut 10 is rotated and moves along thesleeve 9 in an axial direction and in consequence of the oppositeinclination of the spiral keys of the bearing the parts 1 and 2 of thepropeller turn through a small angle relative to each other andadjustment is thereby effected.

The cross section of the propeller shown in Fig. 3 through the twoportions of the blade shows the effect of the adjustment on the commoncross section. The dotted section of one blade portion is moved to thefullline position whereby the aerodynamic pitch and the effective bladearea is changed.

It will now be realized that there has been disclosed a principlerelating to the changing of pitch of a propeller, which can be effectedwithout experiencing difiiculties resulting from large bearing pressurescaused by centrifugal forces.

While I have shown and described the pre-- ferred embodiment of myinvention, I wish it to be understood that I do not confine myself tothe precise details of construction herein set forth, by way ofillustrations, as it is apparent that many changes and variations may bemade therein, by those skilled in the art, without departing from thespirit of the invention, or exceeding the scope of the appended claims.

What is claimed is:

1. A propeller comprising a blade divided longitudinally into two parts,one of said parts being movable with respect to the other about the axisof the propeller shaft.

2. A propeller comprisinga blade having a plurality of sections, onesection of the blade being adapted to slide relative to another sectionabout the propeller axis.

3. A propeller blade consisting of two sections adapted to sliderelative to each other about the main propeller axis.

4. A propeller comprising a blade having two sections formed with hubextensions, a

' bearing mounted between the extensions and means adapted to impartmotion to said bearing whereby the propeller blade sections sliderelative to each other about the main propeller axis.

5. A propeller comprising a blade having two sections formed withintegral hub extensions, a bearing mounted between the extensions andinterlocked therewith, and means adapted to impart motion to saidbearing whereby the propeller blade sections are rotated relative toeach other about the axis of the propeller shaft.

6. A propeller comprising a blade having two sections formed withintegral hub extensions having grooves formed therein, a bearing mountedbetween said extensions and interlocked therewith, and means adapted toimpart longitudinal movement to said hearing whereby the propeller bladesections are rotated relative to each other about the axis of thepropeller shaft.

- 7. A propeller comprising a blade having two sections formed withintegral hub extensions, said extensions having grooves formed therein,a bearing mounted between the extensions, means to interlock the bearingwith the hub extensions comprising keys adapted to fit into the groovesformed in the hub extensions, and means adapted to impart motion to saidbearing whereby the propeller blade sections are rotated relative toeach other about the axis of the propeller shaft.

8. A propeller comprising a blade having two interlocked sections formedwith integral hub extensions, said extensions having spiral groovesformed therein, a bearing mounted between the extensions, means tointerlock the bearing with the hub extension comprising spiral keysadapted to fit into the spiral grooves formed in the hub extensions, andmeans adapted to impart longitudinal and rotary motion to said bearingwhereby the propeller blade sections are rotated relative to each otherabout the axis of the propeller shaft.

- In testimony whereof I ailix my signature.

- MAX M. MUNK.

